Application Analysis Of Slewing Bearings In Various Fields

Slewing bearings, also known as slewing bearings, are large bearings that can simultaneously withstand large axial loads, radial loads and overturning moments. Slewing bearings generally have mounting holes, internal gears or external gears, lubricating oil holes and sealing devices, so that the main engine can have compact structure design, reliable guidance and convenient maintenance.

     Slewing bearings include four-point contact ball bearings with or without gears, external gears and internal gears, double-row angular contact ball bearings, crossed cylindrical roller bearings, crossed tapered roller bearings and three-row cylindrical roller combined bearings, etc. a structural type. Among them, the four-point contact ball bearing has a higher static load capacity; the crossed cylindrical roller bearing has a higher dynamic load capacity; the crossed tapered roller bearing can make the bearing have greater support rigidity and higher rotation through pre-interference precision.     Slewing bearings are widely used in large slewing devices such as hoisting machinery, mining machinery, construction machinery, port machinery, ship machinery, high-precision radar machinery and missile launchers.     Application of slewing bearings in various fields     1. Wind turbine     The yaw bearing is installed at the connection between the tower and the cockpit, and the pitch bearing is installed at the connection between the root of each blade and the hub. Each wind turbine uses one set of yaw bearings and three sets of pitch bearings. The material of the yaw and pitch bearing rings is 42CrMo, the heat treatment adopts the overall quenching and tempering treatment, and the surface of the raceway is quenched. The stress of yaw and pitch bearings is complex, and the impact and vibration they bear are relatively large. Therefore, it is required that the bearing can withstand both impact and large load. The life of the main engine of the wind turbine is required to be 20 years, and the cost of bearing installation is relatively high. Therefore, the life of the yaw and pitch bearings is required to reach 20 years. The hardness of the bearing ring base is 240-280HB, which can withstand impact without plastic deformation. At the same time, the quenching hardness of the raceway surface reaches 55-62HRC, which can increase the contact fatigue life and ensure the long service life of the bearing.     2. Marine cranes     Marine cranes generally use double-row different-diameter balls, four-point contact balls, and three-row roller slewing bearings with internal tooth structure. According to different load-carrying capacity, three-row roller slewing bearings are usually used for heavy-duty cranes, four-point contact ball slewing and Double row reducing ball slewing bearings are used for light cranes.     Since the crane works in the environment of -20°C-+45°C, this type of bearing has higher requirements on the mechanical properties of the material.     3. Offshore platform cranes     According to different load capacity requirements, offshore platform cranes usually use four-point contact ball slewing bearings and three-row roller internal tooth slewing bearings.     The slewing bearings used on offshore platform cranes have special material requirements. The mechanical properties of the materials must ensure the safety factor under the ultimate load. The Charpy impact test of forging samples can reach an average of 42J@-20°C or 27J@-40 °C. Finished bearings must be certified by classification societies.     4. Port mobile crane     Port cranes usually use three-row roller slewing bearings with internal or external teeth with a diameter of 4 meters to withstand high overturning moments.     5. Stacker-reclaimer     The slewing bearings used in stackers and reclaimers usually adopt ball-column joint type, three-row roller type and cross-roller type, and most of them have a diameter of more than 3 meters. Due to the harsh working environment and heavy dust, this type of bearing has the characteristics of high load carrying capacity, long life and good sealing performance.     6. Ferris wheel     Four-point contact ball slewing bearings for ferris wheels, with a large outer diameter of 4100mm and a thickness of 85mm     7. Ship unloader     The slewing bearings used in ship unloaders usually adopt a three-row roller structure with external teeth, with a diameter of about 4 meters.     8. Tower crane     The slewing bearings used in tower cranes usually use small-sized four-point contact ball slewing bearings or double-row ball slewing bearings, with a diameter of no more than 2 meters.     9. Radar Antenna     The short-wave antenna generally uses a turntable bearing with a three-row roller structure, and the rotation speed is slow.     10. Shield machine     The diameter of the turntable bearings for shield machines ranges from 2.5 meters to 6 meters, and some have larger diameters. These bearings work under very harsh conditions. The bearings carry a large load, have strong corrosion resistance, and have a short service life.     11. Ladle turret     Slewing table bearings for ladle turrets usually adopt a three-row roller structure. Because they work under harsh conditions with dust and high temperature, they have high requirements for retainers, grease and sealing strips.     12. Construction machinery     Slewing bearings for construction machinery usually use small-sized four-point contact ball slewing bearings with a diameter of no more than 2 meters.